OK. You are not wrong, the varience of opinion are expressed with denominations with the mainline Protestants who've become liberal over time ,and Protestants who've kept the core beliefs (Evangelicals).
We are also called Christian Fundamentalists, because like all fundamentalists, we champion the return to the fundamental teachings of scripture. Christian Fundamentlism grew as a response to the decline of churches and the rise of Charles Darwin's Evolution.
Historical Protestants are not liberal, but are as we are now. And, in actuality, Salvation is a processes. Unfortunately, OSAS, or Once Saved Always Saved is a misnomer of Eternal Security. The problem with OSAS is that while Eternal Life is given at the point of Faith, one is not completely saved.
It is therefore a process, but it is not done by us at all, but done by the Savior (1 Corinthians 3:11 & Philippians 1:6).
We are saved, Past Tense, as we're promised and given salvation (deliverance from the eternal consequence of sin. At thast point of faith, we are Justified... declared righteous, on the account of the Son).
We are saved, Present Tense, that Christ is continuing to save us (Galatians 2:20). In saving us, we are also being sanctified (set apart aka, made holy).
And, we are saved, Future Tense, in that He will complete the process and bring us to Heaven (John 6:37-39, Romans 8:11, & Jude 1:24). This is summarized in the following verses; the Calvinists like I called this, the Chain of Salvation:
30 And those whom He predestined, He also called; and those whom He called, He also justified [declared free of the guilt of sin]; and those whom He justified, He also glorified [raising them to a heavenly dignity].
- Romans 8:30 ESV